Recently, as high-end products are manufactured with massive information representation, liquid crystal displays (hereinafter abbreviated LCDs) are globally used for portable video cameras, TVs, computer monitors, mobile phones, vehicle navigation systems and the like.
LCD is a light-receiving display that forms a picture by receiving external light. And, light is applied by a backlight provided to a backside of the LCD. The backlight uses a lamp as a light source. In particular, the backlight converts the light of the lamp to planar light having the same brightness and then applies the planar light to an LCD screen.
The general requirements of the backlight include high brightness, high efficiency, uniformity of brightness, long durability, slimness, light weight and low price. In particular, a high brightness characteristic is required for an LCD or TV monitor. As mentioned in the above description, since a backlight is not a self-luminescent display device, a lamp is adopted for the backlight. Therefore, the brightness of an LCD screen is determined by a voltage of an LCD driver, which is supplied by an external circuit.